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Commit 02004681 authored by Antti Palosaari's avatar Antti Palosaari Committed by Mauro Carvalho Chehab
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[media] msi3101: enhance sampling results 



It looks like there is some extra data carried to enhance sampling
results. When you tune to some some weak/empty channel those bits
are always zeroes. When you tune to some channel where is very
strong signals those bits are all zeroes.
Examining those 32-bits reveals shortly there is 16 pieces of 2-bit
numbers. Number seen are 0, 1 and 3 - for some reason 2 is not used.
I used that number to shift bits given amount to left, "increasing"
sampling resolution by 3-bits. It may be wrong, but after some testing
it still provides better signal.

Signed-off-by: default avatarAntti Palosaari <crope@iki.fi>
Signed-off-by: default avatarMauro Carvalho Chehab <m.chehab@samsung.com>
parent 3673b35c

drivers/staging/media/msi3101/sdr-msi3101.c

+67 −53
Original line number Diff line number Diff line
@@ -409,6 +409,7 @@ struct msi3101_state { 
	u32 next_sample; /* for track lost packets */

	u32 sample; /* for sample rate calc */

	unsigned long jiffies;

	unsigned int sample_ctrl_bit[4];

};



/* Private functions */
@@ -429,6 +430,51 @@ static struct msi3101_frame_buf *msi3101_get_next_fill_buf( 
	return buf;

}



/*

 * +===========================================================================

 * |   00-1024 | USB packet

 * +===========================================================================

 * |   00-  03 | sequence number of first sample in that USB packet

 * +---------------------------------------------------------------------------

 * |   04-  15 | garbage

 * +---------------------------------------------------------------------------

 * |   16- 175 | samples

 * +---------------------------------------------------------------------------

 * |  176- 179 | control bits for previous samples

 * +---------------------------------------------------------------------------

 * |  180- 339 | samples

 * +---------------------------------------------------------------------------

 * |  340- 343 | control bits for previous samples

 * +---------------------------------------------------------------------------

 * |  344- 503 | samples

 * +---------------------------------------------------------------------------

 * |  504- 507 | control bits for previous samples

 * +---------------------------------------------------------------------------

 * |  508- 667 | samples

 * +---------------------------------------------------------------------------

 * |  668- 671 | control bits for previous samples

 * +---------------------------------------------------------------------------

 * |  672- 831 | samples

 * +---------------------------------------------------------------------------

 * |  832- 835 | control bits for previous samples

 * +---------------------------------------------------------------------------

 * |  836- 995 | samples

 * +---------------------------------------------------------------------------

 * |  996- 999 | control bits for previous samples

 * +---------------------------------------------------------------------------

 * | 1000-1024 | garbage

 * +---------------------------------------------------------------------------

 *

 * Bytes 4 - 7 could have some meaning?

 *

 * Control bits for previous samples is 32-bit field, containing 16 x 2-bit

 * numbers. This results one 2-bit number for 8 samples. It is likely used for

 * for bit shifting sample by given bits, increasing actual sampling resolution.

 * Number 2 (0b10) was never seen.

 *

 * 6 * 16 * 2 * 4 = 768 samples. 768 * 4 = 3072 bytes

 */



/*

 * Converts signed 10-bit integer into 32-bit IEEE floating point

 * representation.
@@ -438,20 +484,24 @@ static struct msi3101_frame_buf *msi3101_get_next_fill_buf( 
 */

#define I2F_FRAC_BITS  23

#define I2F_MASK ((1 << I2F_FRAC_BITS) - 1)

static uint32_t msi3101_int2float(uint32_t x)

static u32 msi3101_convert_sample(struct msi3101_state *s, u16 x, int shift)

{

	uint32_t msb, exponent, fraction, sign;

	u32 msb, exponent, fraction, sign;

	s->sample_ctrl_bit[shift]++;



	/* Zero is special */

	if (!x)

		return 0;



	/* Negative / positive value */

	if (x & 0x200) {

	/* Convert 10-bit two's complement to 13-bit */

	if (x & (1 << 9)) {

		x |= ~0U << 10; /* set all the rest bits to one */

		x <<= shift;

		x = -x;

		x &= 0x3ff;

		x &= 0xfff; /* result is 12 bit ... + sign */

		sign = 1 << 31;

	} else {

		x <<= shift;

		sign = 0 << 31;

	}
@@ -476,6 +526,7 @@ static int msi3101_convert_stream(struct msi3101_state *s, u32 *dst, 
{

	int i, j, k, l, i_max, dst_len = 0;

	u16 sample[4];

	u32 bits;

#ifdef MSI3101_EXTENSIVE_DEBUG

	u32 sample_num[3];

#endif
@@ -493,6 +544,7 @@ static int msi3101_convert_stream(struct msi3101_state *s, u32 *dst, 
#endif

		src += 16;

		for (j = 0; j < 6; j++) {

			bits = src[160 + 3] << 24 | src[160 + 2] << 16 | src[160 + 1] << 8 | src[160 + 0] << 0;

			for (k = 0; k < 16; k++) {

				for (l = 0; l < 10; l += 5) {

					sample[0] = (src[l + 0] & 0xff) >> 0 | (src[l + 1] & 0x03) << 8;
@@ -500,10 +552,10 @@ static int msi3101_convert_stream(struct msi3101_state *s, u32 *dst, 
					sample[2] = (src[l + 2] & 0xf0) >> 4 | (src[l + 3] & 0x3f) << 4;

					sample[3] = (src[l + 3] & 0xc0) >> 6 | (src[l + 4] & 0xff) << 2;



					*dst++ = msi3101_int2float(sample[0]);

					*dst++ = msi3101_int2float(sample[1]);

					*dst++ = msi3101_int2float(sample[2]);

					*dst++ = msi3101_int2float(sample[3]);

					*dst++ = msi3101_convert_sample(s, sample[0], (bits >> (2 * k)) & 0x3);

					*dst++ = msi3101_convert_sample(s, sample[1], (bits >> (2 * k)) & 0x3);

					*dst++ = msi3101_convert_sample(s, sample[2], (bits >> (2 * k)) & 0x3);

					*dst++ = msi3101_convert_sample(s, sample[3], (bits >> (2 * k)) & 0x3);



					/* 4 x 32bit float samples */

					dst_len += 4 * 4;
@@ -511,9 +563,8 @@ static int msi3101_convert_stream(struct msi3101_state *s, u32 *dst, 
				src += 10;

			}

#ifdef MSI3101_EXTENSIVE_DEBUG

			if (memcmp(src, "\xff\xff\xff\xff", 4) && memcmp(src, "\x00\x00\x00\x00", 4))

			dev_dbg_ratelimited(&s->udev->dev,

						"padding %*ph\n", 4, src);

					"sample control bits %08x\n", bits);

#endif

			src += 4;

		}
@@ -529,9 +580,11 @@ static int msi3101_convert_stream(struct msi3101_state *s, u32 *dst, 
		s->jiffies = jiffies_now;

		s->sample = sample_num[i_max - 1];

		dev_dbg(&s->udev->dev,

				"slen=%d samples=%u msecs=%lu sampling rate=%lu\n",

				"slen=%d samples=%u msecs=%lu sampling rate=%lu bits=%d.%d.%d.%d\n",

				src_len, samples, msecs,

				samples * 1000UL / msecs);

				samples * 1000UL / msecs,

				s->sample_ctrl_bit[0], s->sample_ctrl_bit[1],

				s->sample_ctrl_bit[2], s->sample_ctrl_bit[3]);

	}



	/* next sample (sample = sample + i * 384) */
@@ -833,45 +886,6 @@ static int msi3101_buf_prepare(struct vb2_buffer *vb) 
	return 0;

}



/*

 * +===========================================================================

 * |   00-1024 | USB packet

 * +===========================================================================

 * |   00-  03 | packet address

 * +---------------------------------------------------------------------------

 * |   04-  15 | garbage

 * +---------------------------------------------------------------------------

 * |   16- 175 | samples

 * +---------------------------------------------------------------------------

 * |  176- 179 | padding

 * +---------------------------------------------------------------------------

 * |  180- 339 | samples

 * +---------------------------------------------------------------------------

 * |  340- 343 | padding

 * +---------------------------------------------------------------------------

 * |  344- 503 | samples

 * +---------------------------------------------------------------------------

 * |  504- 507 | padding

 * +---------------------------------------------------------------------------

 * |  508- 667 | samples

 * +---------------------------------------------------------------------------

 * |  668- 671 | padding

 * +---------------------------------------------------------------------------

 * |  672- 831 | samples

 * +---------------------------------------------------------------------------

 * |  832- 835 | padding

 * +---------------------------------------------------------------------------

 * |  836- 995 | samples

 * +---------------------------------------------------------------------------

 * |  996- 999 | padding

 * +---------------------------------------------------------------------------

 * | 1000-1024 | garbage

 * +---------------------------------------------------------------------------

 *

 * bytes 4 - 7 could have some meaning?

 * padding is "00 00 00 00" or "ff ff ff ff"

 * 6 * 16 * 2 * 4 = 768 samples. 768 * 4 = 3072 bytes

 */

#ifdef MSI3101_CONVERT_IN_URB_HANDLER

static int msi3101_buf_finish(struct vb2_buffer *vb)

{